Isotropic to nematic transition in semiflexible polymer melts

Monte Carlo simulations are reported for the isotropic to nematic phase transition in semiflexible polymer melts. The molecules are modelled as tangent hard sphere chains with a bending energy that can be used to tune the stiffness of the chains. In the rod limit an isotropic to nematic transition occurs at high pressures. For freely-jointed chains no nematic phase is found, but a fairly sharp transition to a nematic phase is observed when the stiffness is increased at fixed density for sufficiently high densities. In semiflexible chains the isotropic to nematic transition is accompanied by a discontinuous change in the chain dimensions. The simulations show that existing theories are not quantitatively accurate for the isotropic to nematic transition in semiflexible chains.